Digital motion picture restoration involves a variety of image processing operations that require a considerable amount of computations and take a relatively long amount of time, even with powerful computers. An example of a computation-intensive image processing technique is motion estimation, which is required for high fidelity repair. Generally, motion estimation allows a defective region of an image to be replaced with a corresponding image region from a previous or subsequent image frame.
Longer processing times are acceptable if the computations are conducted automatically, without user interaction. Numerous complex algorithms have been developed for automatic image sequence restoration. For a detailed discussion of such image restoration techniques, see, for example, Anil Kokaram, “Motion Picture Restoration,” (Springer, 1998). Currently available image restoration techniques, however, do not provide a complete solution. Generally, currently available image restoration techniques suffer from incomplete repair or false detection (or both), resulting in image artifacts. Thus, human intervention is eventually required to complete the image restoration and obtain high quality artifact-free restoration.
Image restoration techniques typically require an operator to work with the original image sequence and the automatically repaired image sequence in an interactive process until the operator is satisfied with the restoration. Generally, the operator reviews the repaired image sequence and accepts, rejects or further modifies each restored image portion. This workflow has certain disadvantages, which if overcome, could greatly improve the efficiency and quality of the restoration process. For example, currently available image restoration systems do not provide a clear indication of areas that have been repaired automatically in current or previous steps. Thus, the operator must carefully investigate every frame in order to determine whether any artifacts were introduced. In addition, current systems do not allow a defect that appears in a number of consecutive frames, for example, caused by dirt on the camera lens, to be repaired in an efficient manner.
A need therefore exists for a method and apparatus for removing defects from images that provides a better user interface for image sequence repair. A further need exists for a method and apparatus for removing defects from images that provides an improved mechanism for repairing a defect that appears in a number of consecutive frames.